The proposed work represents a multidisciplinary effort to describe further the normal relationship between the brain and its vasculature, as well as the pathogenesis, diagnosis, and treatment of selected aspects of acute cerebrovascular disease. Studies in patients and laboratory animals will use new tracer techniques, cyclotron-produced radiopharmaceuticals, appropriate mathematical models and emission tomography to make quantitative, in vivo measurements of tissue substrate utilization, tissue acid-base status, tissue biochemical composition (e.g., lipid content), intravascular localization of radiolabeled blood constituents (e.g., platelets), and specific receptor localization. Basic development work in all aspects of this work (e.g., radiochemistry, mathematical modeling, instrumentation development) will be conducted by a multidisciplinary group. Specific patient studies will focus on the role of platelets in cerebrovascular disease, the effect of subarachnoid hemorrhage and vasospasm in cerebral hemodynamics and metabolism, and the efficacy of superficial temporal artery to middle cerebral artery anastomosis in correcting hemodynamically significant occlusive, intracranial, cerebrovascular disease involving large vessels.